Segmental analysis of SPECT 99mTc-methoxy isobutyl isonitrile and 201Tl myocardial imaging in ischaemic heart disease.

To study the potential usefulness of 99mTc-methoxy isobutyl isonitrile (99mTc-MIBI) as a substitute for 201Tl in assessing patients with ischaemic heart disease, 24 patients underwent 1 day rest and exercise 99mTc-MIBI single photon emission computerised tomography (SPECT) 1 week after SPECT exercise 201Tl. All patients were catheterized within 1 month after myocardial imaging. In 17 patients, resting first pass radionuclide angiography (FPRNA) was performed with 99mTc-MIBI. The heart to lung ratio for 99mTc-MIBI and 201Tl was calculated both at rest and exercise. The segmental analysis for myocardial perfusion reveals that 87/96 segments (91%) were correctly classified by SPECT 201Tl and 84/96 segments (88%) were correctly classified by 99mTc-MIBI. A significant correlation was present between LVEF measured by 99mTc-MIBI FPRNA and contrast ventriculography (r = 0.85, P less than 0.0001). The heart to lung ratio both at rest and exercise for 99mTc-MIBI is significantly higher than 201Tl (P less than 0.01 and less than 0.001 respectively). We conclude that 99mTc-MIBI is a promising agent for simultaneous evaluation of myocardial perfusion and cardiac function.

Problems of duodenogastric reflux in Tc-99m Hexa MIBI planar, tomographic and bull's eye display.

Tc-99m Hexa MIBI (RP-30) is excreted through hepatobiliary pathways. Myocardial imaging with RP-30 is recommended 45-60 minutes after injection. During this waiting period duodenogastric reflux (DGR) is occasionally seen. Fundal activity due to duodenogastrix reflux presents problems in planar, tomographic, and Bull's eye display. The authors recommend in those cases to give the patient a light meal and wait 15-30 minutes more for the gastric activity to empty in the small intestine before starting myocardial imaging.